Morphology

Coenobita perlatus are approximately 80mm long and 80g in body mass. They occupy the multicolored discarded shells of gastropods in order to protect their soft, coiled abdomen and inner organs such as the liver and gonads. These land hermit crabs are decapods, which means they have 10 legs (5 pairs): The first pair is modified as the claws or chelipeds (pinchers), and two pairs of legs are used for walking. The next pair, the claws, are used for defense and transporting food and water to the their mouth. The last two pairs are highly modified but are used more for cleaning than holding on to the shell. When walking, these crabs drag their shells along, but despite this burden, they can run quickly. Each C. perlatus has a loosely fitting carapace that covers the forepart of the body. Coenobita perlatus prefer shells that fit snugly in order to prevent evaporation of moisture and to protect their soft abdomens. Coenobita perlatus have four antennae that help them to sense their surroundings. They have shown some geographic physical variation, but this variations have not been studied in depth.

Male and female C. perlatus can only be distinguished when they are out of their shells. Both the female and male genital pores are located on the coxal ventral surface of each pereiopod (on an appendage of one of the first five abdominal segments), and a long coxal tube (an extension of a pereiopod which is joined broadly to lateral margins of tergites) is present in the male.